Discontinued Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax	$ 0.0	$ 49.2	$ 0.0
Revenues		0.0	340.9
Cost of revenues		0.0	(307.0)
Operating expenses		(0.7)	(22.5)
Income / (loss) from discontinued operations before income tax	0.0	(0.7)	11.4
Income tax expense / (benefit) from discontinued operations	0.0	19.2	(1.0)
Net income from discontinued operations	$ 0.0	29.3	12.4
Cash Provided by (Used in) Operating Activities, Discontinued Operations		(0.7)	35.8
Cash Provided by (Used in) Investing Activities, Discontinued Operations		$ 75.5	$ 0.5